Subterranean hydrocarbon containing formations penetrated by well bores are commonly stimulated by creating fractures in the formations. Typically a fracturing fluid such as a gelled aqueous fluid is pumped into the formation at a rate and pressure such that fractures are created and extended therein. A propping material such as sand is typically deposited in the fractures so that they are prevented from completely closing when the formation is returned to production and provide flow passages through which hydrocarbons readily flow to the well bore.
Wells in certain geographic locations such as in shale formations may require an initial fracturing to be economically productive. After a number of years, the hydrocarbon production level will decline to a level of marginal economic viability. At that time the well is evaluated for possible restimulation. Because restimulation costs a fraction of the cost of drilling and initially fracturing a well, restimulation may be attempted when there is only a fair chance of obtaining a modest increase in production level.
Self-degrading particulates have been used for various processes including restimulation of oil and gas wells. Before a refracturing treatment, new perforations are added to promote better lateral coverage. Self-degrading particulates are incorporated into the refracturing treatment to provide better lateral coverage and increase stimulation effectiveness. The refracturing treatment includes a continuous pumping of fracturing fluid, with varying levels of propping material and self-degrading particulates added to the fracturing fluid at different times in accordance with a treatment schedule. The treatment schedule includes multiple phases of fluid injection with propping material separated by diversion sequences of fluid injection with self-degrading particulates.